The growth in air traffic density is compelling an increase in arrival rates. This involves the instigation of time constraints and maximum reduction in inter-aircraft separations which then become very tricky to maintain when the speeds are low, as in the final approach to a landing runway, and if the wind context changes. The bottleneck for air traffic is essentially during the approach phase because of the frequent uniqueness of the runway in service and of its associated approach, and of the obligatory maintaining of a safety separation distance between aircraft in the final approach so as to reduce the risks of collision or stalling related to wake turbulence or to unforeseen manoeuvres such as go-arounds. Today, this separation is essentially managed through the speed which is maintained at least equal between two successive aircraft. The flow of aircraft on landing is thus maximized by maintaining this minimum distance.
It may happen, however, that an approach procedure necessitates a large turn (minimum)120° as in turnaround procedures or traditional manoeuvres with a tailwind section (“circle to land”). Except, if a relatively strong wind exists, a major problem can occur when two aeroplanes following one another at the same speed are temporarily brought closer together on account of the wind. FIG. 1 represents an example of such a case. A first aircraft A1 flying along a trajectory 100 trails a second aircraft A2 flying along the same trajectory 100. The trajectory comprises an arrival segment 101, a turn 102 and a final segment 103 terminating at a landing runway 104. The arrival segment 101 and the final segment 103 are parallel. The first aircraft A1 is positioned at the end of the arrival segment 101. The second aircraft A2 is positioned at the start of the final segment 103. When the second aircraft A2 is situated on the final segment 103, it experiences a headwind Ve which slows it down, while the first aircraft A1 being situated on the arrival segment 101 is accelerated by a tailwind Ve. For a time equal to the initial separation time Tsep1 (typically 90 seconds or more), the separation is no longer maintained. The separation time Tsep2 is then less than the initial separation time Tsep1. This forces the first aeroplane A1 to reduce its air speed at the risk of attaining a minimum safety speed (stall protection) below which the aeroplane must not descend. Moreover, the inertia of the engines limits the effectiveness and reactivity in the case of wind and requires increased separations.